Plate-type heat pipe and method for manufacturing the same

ABSTRACT

A plate-type heat pipe includes a base plate having a first wick structure secured thereon and a covering plate mounted on the base plate. The base plate includes a central heat-absorbing plate and a pair of extending plates angling upwardly from opposite ends of the heat absorbing plate. The first wick structure includes a first adhering portion securely fixed to a top surface of a central portion of the heat absorbing plate, two second adhering portions angling upwardly from opposite ends of the first adhering portion and securely fixed to the top surface of lateral portions of the heat absorbing plate and top surfaces of the extending plates. The first adhering portion is thinner than the second adhering portion, and the second adhering portion thins from a central portion to opposite ends thereof.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to plate-type heat pipes and, more particularly, to a plate-type heat pipe with enhanced heat dissipation efficiency. The plate-type heat pipe has a wick structure therein; the wick structure has a cross-section with a varied thickness.

2. Description of Related Art

Generally, plate-type heat pipes efficiently dissipate heat from components such as central processing units (CPU). Referring to FIGS. 7-8, a conventional plate-type heat pipe comprises a top plate 100, a base plate 101 engaging the top plate 100, and a wick structure 102 of uniform thickness mounted on the base plate 101. A heat absorbing portion 103 extends downwardly from a center portion of the base plate 101, contacting the heat-generating components. When heat from a component enters the plate-type heat pipe via its heat absorbing portion 103, working fluid in the wick structure 102 absorbs the heat and vaporizes. If the wick structure 102 is too thick, the vapor remains therein, increasing heat resistance of the heat pipe and raising a temperature of the base plate 101, possibly inflicting damage thereon. If the wick structure 102 is too thin, the working fluid vaporizes too quickly, damaging the wick structure 102.

It is therefore desirable to provide a plate-type heat pipe which has a wick structure of optimum thickness to engage the plate-type heat pipe.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the present embodiments can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present embodiments. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.

FIG. 1 is a cross-section showing a plate-type heat pipe formed in a mold in accordance with a first embodiment of the disclosure.

FIG. 2 is a cross-section of the plate-type heat pipe of FIG. 1.

FIG. 3 is a cross-section showing a plate-type heat pipe formed in a mold in accordance with a second embodiment of the disclosure.

FIG. 4 is a cross-section of the plate-type heat pipe of FIG. 3.

FIG. 5 is a cross-section showing a plate-type heat pipe formed in a mold in accordance with a third embodiment of the disclosure.

FIG. 6 is a cross-section of the plate-type heat pipe of FIG. 5.

FIG. 7 is an exploded, cross-section of a related plate-type heat pipe.

FIG. 8 is an assembled view of FIG. 7.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIGS. 1-2, a method for manufacturing a plate-type heat pipe 10 in accordance with a first embodiment of the disclosure is detailed as follows.

A bowl-shaped base plate 11 and a covering plate 13 are provided. The base plate 11 comprises a central heat absorbing plate 112, a pair of extending plates 114 angling upwardly from opposite ends of the heat absorbing plate 112, two engaging plates 116 extending outwardly from ends of the extending plates 114 respectively and facing apart, and two sidewalls 118 extending upwardly from ends of the engaging plates 116.

A mold 15 is provided. The mold 15 comprises a first mold 151 and a second mold 153. The first mold 151 encloses the base plate 11 therein. The first mold 151 and the base plate 11 define a first cavity 152 therebetween. The second mold 153 encloses the covering plate 13 therein. The second mold 153 and the covering plate 13 define a second cavity 154 therebetween. A cross-section of the second cavity 154 is rectangular. The first cavity 152 comprises a first receiving portion 1522 corresponding to a central portion of the heat absorbing plate 112 of the base plate 11, two second receiving portions 1524 angling outwardly from opposite ends of the first receiving portion 1522 and corresponding to lateral portions of the heat absorbing plate 112 and the extending plates 114 of the base plate 11, and two third receiving portions 1526 extending outwardly from ends of the second receiving portions 1524 and corresponding to the engaging plates 116 of the base plate 11. The first, second and third receiving portions, 1522, 1524, 1526 connect and communicate with each other in series. A cross-section of the first receiving portion 1522 is rectangular. A cross-section of the second receiving portion 1524 is pentagonal. The third receiving portion 1526 comprises a first connecting portion 1526 a angling outwardly from an end of the second receiving portion 1524 and a second connecting portion 1526 b extending outwardly from an end of the first connecting portion 1526 a. A cross-section of the first connecting portion 1526 a of the third receiving portion 1526 is trapezoidal. A cross-section of the second connecting portion 1526 b of the third receiving portion 1526 is rectangular. The second receiving portion 1524 of the first cavity 152 is deeper than the first receiving portion 1522. Depth of the second receiving portion 1524 first increases and then decreases along a laterally outwardly direction. The third receiving portion 1526 is deeper than the second receiving portion 1524 of the first cavity 152. Depth of the first connecting portion 1526 a of the third receiving portion 1526 of the first cavity 152 increases from an inner end connected with the second receiving portion 1524 to an outer end opposite to the inner end. An inner end of the second connecting portion 1526 b is of the same depth as the outer end of the first connecting portion 1526 a.

A first metal powder is filled into the first cavity 152 and a second metal powder is filled into the second cavity 154. The first and second metal powder are copper powder. Particle size of the first metal powder is less than that of the second metal powder. The first metal powder filled in the first cavity 152 and the second metal powder filled in the second cavity 154 are heated to a high temperature, sufficient to execute sintering, to obtain a sintered first wick structure 16 securely fixed to a top surface of the base plate 11 and a sintered second wick structure 17 securely fixed to a bottom surface of the covering plate 13. The first wick structure 16 and the second wick structure 17 are porous, with apertures of the first wick structure 16 fewer than those of the second wick structure 17. The first wick structure 16 comprises a first adhering portion 161 securely fixed to a top surface of the central portion of the heat absorbing plate 112 of the base plate 11, two second adhering portions 163 securely fixed to top surfaces of the lateral portions of the heat absorbing plate 112 and the extending plates 114 of the base plate 11, and two third adhering portion 165 securely fixed to top surfaces of the engaging plates 116 of the base 11. The third adhering portion 165 receives a first joining portion 1651 in the first connecting portion 1526 a and a second joining portion 1653 in the second connecting portion 1526 b of the third receiving portion 1526 of the first cavity 152. A top surface of the second adhering portion 163 and a top surface of the first joining portion 1651 of the third adhering portion 165 of the first wick structure 16 are coplanar.

The first mold 151 and the second mold 153 of the mold 15 are removed from the first and second wick structures 16, 17 respectively. The base plate 11 with the first wick structure 16 attached thereto and the covering plate 13 with the second wick structure 17 attached thereto are assembled together. A chamber 18 is defined between the first and second wick structures 16, 17 and the chamber 18 is vacuumed and filled with a working fluid (not shown) such as water, alcohol, methanol, or the like, and sealed. The disclosed plate-type heat pipe 10 is thus obtained. In this state, opposite ends of the second wick structure 17 and the second joining portions 1653 of the third adhering portions 165 of the first wick structure 16 are combined.

In this embodiment, a cross-section of the first adhering portion 161 of the first wick structure 16 is rectangular. A cross-section of the second adhering portion 163 of the first wick structure 16 is pentagonal. A cross-section of the first joining portion 1651 of the third adhering portion 165 of the first wick structure 16 is trapezoidal. A cross-section of the second joining portion 1653 of the third adhering portion 165 of the first wick structure 16 is rectangular. A cross-section of the second wick structure 17 is rectangular. The first adhering portion 161 of the first wick structure 16 is thinner than the second wick structure 17. Work fluid contained in the first adhering portion 161 of the first wick structure 16 absorbs heat and is vaporized quickly to generate vapor. The vapor then reaches the second wick structure 17. The second adhering portion 163 of the first wick structure 16 is thicker than the first adhering portion and thins from a central portion to distal ends thereof. Third adhering portion 165 thickens from an inner end connected with the second adhering portion 163 to an outer end opposite to the inner end. The second and third adhering portions 163, 165 collect condensate work fluid from the second wick structure 17. When generated heat enters the plate-type heat pipe 10 via heat absorbing portion 112, the work fluid contained in the first adhering portion 161 of the first wick structure 16 absorbs the heat and vaporizes, and the working fluid contained in the second and third adhering portions 163, 165 of the first wick structure 16 flows to the first adhering portion 161.

Referring to FIGS. 3-4, a plate-type heat pipe 20 is manufactured using the method previously described, differing only in that configuration of the first connecting portion 2526 a of the first cavity 252 is different from that of the first connecting portion 1526 a of the first cavity 152 of the first embodiment. The first connecting portion 2526 a is shallower than the first connecting portion 1526 a of the first embodiment. A joint of the first connecting portion 2526 a and the second receiving portion 2524 defines a hollow protruding portion 2517 thereof. The protruding portion 2517 angles upwardly from the joint of the first joining 2526 a and the second receiving portion 2524. The first joining portion 2651 of first wick structure 26 is thinner than the first joining portion 1651 of the first wick structure 16 of the first embodiment. A step is formed at a joint of the first joining portion 2651 and the second adhering portion 263.

Referring to FIGS. 5-6, a plate-type heat pipe 30 is manufactured using the method previously described, differing only in that configuration of the first connecting portion 3526 a of the first cavity 352 is different from that of the first connecting portion 1526 a of the first cavity 152 of the first embodiment. A cross-section of an outer end of the first connecting portion 3526 a is rectangular. The outer end of the first connecting portion 3526 a is shallower than an outer end of the first connecting portion 1526 a. Thus, a cross-section of an outer end of a first joining portion 3651 of the first wick structure 36 is rectangular. The outer end of the first joining portion 3651 is thinner than the first joining portion 1651 of the first embodiment. A chamber 38 of the plate-type heat pipe 30 is larger than the chamber 18 of the plate-type heat pipe 10 of the first embodiment. Therefore, the vaporized work fluid contained in the chamber 38 is cooled quickly and the heat dissipation efficiency of the plate-type heat pipe 30 is enhanced.

It is believed that the disclosed embodiments and their advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the disclosure or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments of the disclosure. 

1. A plate-type heat pipe comprising: a base plate comprising a central heat absorbing plate and a pair of extending plates angling upwardly from opposite ends of the heat absorbing plate; a covering plate mounted on a top of the base plate; and a first wick structure fixed to a top surface of the base plate, the first wick structure comprising a first adhering portion securely fixed to a central portion of a top surface of the heat absorbing plate of the base plate, two second adhering portions angling upwardly from opposite ends of the first adhering portion and securely fixed to lateral portions of the top surface of the heat absorbing plate and top surfaces of the extending plates of the base plate; wherein the first adhering portion is thinner than each of the second adhering portions of the first wick structure, and the each of the second adhering portions thins from a central portion to distal ends thereof.
 2. The plate-type heat pipe as in claim 1, wherein a second wick structure is fixed to a bottom surface of the covering plate and connects with the first wick structure, the second wick structure being thicker than the first adhering portion of the first wick structure.
 3. The plate-type heat pipe as in claim 1, wherein the first wick structure comprises a first metal powder, and the second wick structure comprises a second metal powder.
 4. The plate-type heat pipe as in claim 3, wherein a particle size of the first metal powder of the first wick structure is smaller than a particle size of the second metal powder of the second wick structure.
 5. The plate-type heat pipe as in claim 1, wherein a cross section of the first adhering portion of the first wick structure is rectangular and a cross section of the each of the second adhering portions of the first wick structure is pentagonal.
 6. The plate-type heat pipe as in claim 1, wherein the base plate further comprises two engaging plates extending outwardly from ends of the two extending plates respectively, the first wick structure further comprises two third adhering portions extending from the two second adhering portions and fixed to top surfaces of the two engaging plates.
 7. The plate-type heat pipe as in claim 6, wherein the third adhering portion comprises a first joining portion angling upwardly from an end of a corresponding second adhering portion and a second joining portion extending outwardly from an end of the first joining portion, wherein thickness of the first joining portion increases from an inner end to an outer end.
 8. The plate-type heat pipe as in claim 7, wherein a top surface of the corresponding second adhering portion and a top surface of the first joining portion of the third adhering portion are coplanar.
 9. The plate-type heat pipe as in claim 8, wherein the first joining portion is thinner than the second joining portion and the outmost end of the first joining portion is as thick as an inner end of the second joining portion of the third adhering portion of the first wick structure.
 10. The plate-type heat pipe as in claim 7, wherein a step angles outwardly from a joint of the first joining portion of the third adhering portion and the corresponding second adhering portion of the first wick structure.
 11. The plate-type heat pipe as in claim 10, wherein the first joining portion is thinner than the second joining portion and the outmost end of the first joining portion is thinner than an inner end of the second joining portion of the third adhering portion of the first wick structure.
 12. The plate-type heat pipe as in claim 7, wherein a cross section of the second joining portion is rectangular and a cross section of the first joining portion is trapezoidal.
 13. A method for manufacturing a plate-type heat pipe comprising: providing a base plate, the base plate comprising a heat absorbing plate and two extending plates angling upwardly from opposite ends of the heat absorbing plate; providing a first mold having a structure corresponding to the base plate, the first mold engaging the base plate to cooperatively define a first cavity, the first cavity comprising a first receiving portion corresponding to a central portion of the heat absorbing plate of the base plate, and two second receiving portions angling outwardly from opposite ends of the first receiving portion and corresponding to lateral portions of the heat absorbing plate and the extending plates of the base plate, wherein the first receiving portion of the first cavity is shallower than each of the second receiving portions of the first cavity, and the each of the second receiving portions shallows from a central portion to distal ends thereof; providing a covering plate and a second mold, the second mold engaging the covering plate to cooperatively define a second cavity; filling a first metal powder into the first cavity and a second metal powder into the second cavity; heating the first and second metal powders to obtain a first wick structure fixed to a top surface of the base plate and a second wick structure fixed to a bottom surface of the covering plate, the first wick structure comprising a first adhering portion securely fixed to a top surface of the central portion of the heat absorbing plate of the base plate, two second adhering portions securely fixed to the surface of the lateral portions of the heat absorbing plate and top surfaces of the extending plates of the base plate; removing the first and second molds from the first and second wick structures respectively; assembling the first and second wick structures and the covering and base plates together with a chamber defined between the first and second wick structures; and injecting the chamber with a work fluid; evacuating the chamber by vacuum; and sealing the chamber.
 14. The method as in claim 13, wherein the second cavity is deeper than the first receiving portion of the first cavity.
 15. The method as in claim 13, wherein the base plate further comprises two engaging plates extending outwardly from ends of the extending plates respectively and facing apart, the first mold of the mold enclosing the engaging plates to define two third receiving portions between the engaging plates of the base plate and the first mold, and two third adhering portions of the first wick structure are formed in the third receiving portions and fixed to top surfaces of the engaging plates of the base plate.
 16. The method as in claim 15, wherein each of the third receiving portions comprises a first connecting portion angling outwardly from an end of a corresponding one of the second receiving portions and a second connecting portion extending outwardly from an end of the first connecting portion, the first connecting portion being shallower than the corresponding one of the second connecting portions.
 17. The method as in claim 16, wherein the first connecting portion of the third receiving portion deepens from an end connected with the second receiving portion to an end connected with the second connecting portion of the each of the third receiving portions.
 18. The method as in claim 17, wherein an outmost end of the first connecting portion of the each of the third receiving portions is shallower than the second connecting portion of the each of the third receiving portions. 